Yeah, both sides of my parents family were riddled with alcoholics. But not my mother and not any of my 3 siblings. But I don't think that matters.
I was the same,drank alone, haven't drank in social situations for years.
I think, for me, I get smashed when drinking alone, because I drink at my own speed (fast) and because I didn't interact with anyone while drinking alone, I couldn't judge how drunk I was getting (usually very) until I suddenly woke up wherever I'd passed out, hours later.
But to me, drinking is a personal choice. There is no urge to drink so strong, that you cannot choose to over-rule it.